Further to the post below, Rex Ryan's granddaughter, Elspeth Caton, discovered the following fascinating newspaper article, probably from the Fleetwood Chronicle. The date is uncertain, but judging from the evidence of other articles in the clipping, it appears to date to about May 1926.
So it appears there are still a couple of Rex Ryan novels to be found. Kudos to the first person to discover these books!
A note of caution, though - I'm not sure that The Tyranny of Virtue was a bestseller in Australia - there are only two references to it in the NLA's digitised Australian newspapers - for the copies sent to The Sydney Morning Herald and the Melbourne Argus. And no copy exists at any library in the UK, which might suggest it is unknown in this country!